Neuroscience: Where does it hurt? How?

This conference on pain neuroimaging and the law has set itself a difficult goal:

The issue of the existence or extent of pain comes up hundreds of thousands of times each year in the United States legal system, through personal injury suits, disability determinations, and workers compensation. Current methods of detecting pain are well short of perfect. The science of pain is being revolutionized by neuroimaging technologies, which may in turn have important implications for the law. The goal of this conference is to explore whether and how neuroimaging can help the law deal with claims about individuals’ pain.

My sense is that neuroimaging can help somewhat, but only somewhat.

When I first learned about Mario Beauregard's studies of people in a state of deep mystical contemplation, which we discuss in The Spiritual Brain, I asked him, "How do you know they aren't just faking it?"

He replied, "Oh, that would be no problem. Then they would generate plenty of beta waves but no theta waves, typical of deep meditation."

My guess is that, in the same way, neuroimaging technologies could help identify situations where people are simply faking an injury. (Like the legendary insurance disability claimant who is filmed playing rugby .... )

But many real life situations are much more complex. Some people magnify pain, some diminish it. Some choose to ignore pain. Some cope with it much more effectively than others. For some people, pain brings sympathetic attention, and for others it doesn't.

That was brought home to me when I was having a baby in 1973.

True to my upbringing, I remained silent about any discomfort during labour. But I was horrified to hear a woman down the hall shrieking something like "Jesus!" "Mary!" "Jesus!" "Mary!"

"Can't anything be done for her?", I asked my nurse, "Will she die? Will the baby die?"

"You mustn't worry," the nurse reassured me. "She is going to be fine and the baby will be fine too. In her culture, it is okay to scream like that."

That wise nurse did not assess pain or discomfort merely by the level of self-expression because that varies with culture.

Similarly, if you think that a shooting pain is a mere discomfort, you will experience it differently than if you think that it warns of an impending heart attack.

There is brute fact, to be sure, but there is also interpretation of the fact. The human experience of pain includes both.

Hat tip: Stephanie West Allen at Brains on Purpose

See also:

Finally, an idea! (which recounts a very interesting experiment on pain)

Neuroscience: Making sense of uncontrollable itching

Commentator Dinesh D'Souza on stuff he didn't know - like the power of the placebo effect

Placebo effect: Your mind's role in your health

Neuroscience watch: Another controversial new finding about nerves

In a controversial new finding, written up at Science Daily, physicists at the Niels Bohr Institute at Copenhagen University

Danish scientists challenge the accepted scientific views of how nerves function and of how anesthetics work. Their research suggests that action of nerves is based on sound pulses and that anesthetics inhibit their transmission.

Surprisingly, although anaesthetics have been in use for about 150 years, no one knew exactly how they work. The physicists argue that they work by changing the melting point of nerve membranes, so that they cannot transmit waves.

The standard textbook view has been that nerves send electrical impulses along their length (and presumably anaesthetics disrupt that). That explanation troubled physicists because the process should generate heat, but it doesn't.

David deWitt, however, writes to me urging caution:

I am quite skeptical of the claim (without reading the original paper). There is a good deal of electrophysiological studies that clearly demonstrate that an action potential is triggered electrically. You can attach electrodes to neurons and hyper/hypo polarize them and alter the activity. There are ligand gated and voltage gated ion channels that can be activated or blocked and it is the depolarization of the synaptic membrane that triggers the calcium channels that activate the machinery associated with vesicular docking and release of neurotransmitter at the synapse. You can electrically stimulate the neuron and this will trigger the action potential. It has been shown to be necessary and sufficient. Scientists have long worked out the process of opening and closing of potassium, sodium and calcium channels. You can block these and prevent proper functioning of the neuron.

Note that it is described as "theoretical" in other words they didn't actually measure any mechanical pulses or sound--they merely suggested it as a possibility and an explanation for the effects of anesthesia.

One of the rationales was the fact that different chemicals worked as anesthesia and they depend on the solubility in olive oil. No doubt this solubility is related to how it can penetrate the cell membrane. Just because different compounds have the same effect on a neuron does not mean that they work by the same mechanism. There can be several different mechanisms that are impacted, but all resulting in the same effect.


This is significant because anesthesia does not affect all neuronal populations in the same way. If it were just a matter of a non-specific sound blocking mechanism, then ALL neurons should be simultaneously affected. This should include all of your motor and autonomic neurons as well (the ones that control breathing, peristalsis etc.) However, this is not the case.

It is possible that a rush of ions into the neuron could generate a mechanical pulse as well as an electrical signal, so I want to be careful here. But it would seem that it would have more to do with a change in volume/density than it would in the production of sound.

Instead of what is the sound of one hand clapping, what is the sound of a 100 million potassium ions flowing through a ~2 angstrom hole in a second?

This is all kind of interesting, especially in view of an earlier new finding that brain cells communicate with each other not just at the synapses but along their length.

Anaesthetics exist to relieve pain, and pain is, after all, an experience of the mind as well as a state of the brain. Understanding the true relationship between the mind and the brain will certainly require neuroscientists to develop a more accurate account of how neurons operate.

Toronto-based Canadian journalist Denyse O'Leary (www.designorchance.com) is the author of the multiple award-winning By Design or by Chance? (Augsburg Fortress 2004), an overview of the intelligent design controversy, and of Faith@Science. She was named CBA Canada's Recommended Author of the Year in 2005 and is co-author, with Montreal neuroscientist Mario Beauregard, of the forthcoming The Spiritual Brain: A neuroscientist's case for the existence of the soul (Harper 2007).

If it hurts you more than it hurts someone else, are you just a sissy?

Not necessarily. The old "telegraph" model of pain is being replaced by a model that looks more like the Internet:

... in the last decade or so, psychologists and other pain researchers are coming around to a new definition of just what is pain — and how the experience looks to be different in men and women.

Gone is the old telegraph model that served medical science for thousands of years: You put your hand in a hot fire you felt the pain of the burn until the tissue eventually healed.

In its place, some scientists are putting forward the notion that pain ricochets through the body more like the way the internet works: The initial experience sets off a complex chain of reactions involving one's general health, genetic makeup, brain chemistry and perhaps even how one has come to think about pain in the first place.

Even more, the placebo effect and its evil twin the nocebo effect, functions of your own mind, play a great role in what you will or won't feel.

Much, though, is clearly in the deep recesses of the mind. Two years ago, for example, researchers in London and Pittsburgh hypnotized otherwise healthy people and told them they were in acute pain. Brain scans then showed these subjects had virtually the same electro-chemical activity as patients with actual ailments — another indicator pain can actually originate in the mind.

Obviously, if it hurts you, it hurts. But no one single standard of pain can be applied to everyone because many factors, including your own mind, play a role in what you are experiencing. Remember that when someone tells you that your mind does not really exist.

My other blog is the Post-Darwinist, which keeps tabs on the intelligent design controversy.